Spark plug structure



Nov. 4l0, 1942. E. B. NowoslELsKl SPARK PLUG STRUCTURE Filed Aug- 2, 1929 Patented Nov. 10, 1942 2,301,512 s raax PLUG STRUCTURE Edward B. Nowosielski, Bloomfield, N. J., assignor, by mesne assignments, to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application August 2, 1929, Serial No. 382,985

29 Claims. l(Cl. 123-169) 'I'his invention relates to ignition systems for internal combustion engines of the type embodying spark plugs for igniting the charge in the cylinders of the engine.

One of the objects of the invention is to provide an ignition device of novel and improved construction which is both mechanically and electrically strong and is capable of long service without mechanical or electrical faults.

Another object is to provide an improved spark plug structure embodying novel means for formingl a gas-tight seal to prevent the escape of gases from. the engine cylinder, loss of compression in the cylinder, etc.

Another object is to provide an improved ignition device embodying novel means for completely shielding all of the electrical parts thereof to prevent interference with the operation of other electrical apparatus, such as a radio set.

A still further object is to provide an ignition device embodying a spark plug and novel shielding means therefor which means may be readily and easily attached to or detached from the plus.

A further object is to provide an ignition device of novel construction embodying a spark plug, a lead theref. and shielding means for the plug and lead, the shielding means and the llead being rotatably attached to the plus whereby they may be adjusted around the plug to any desired angular position.

Another object is to provide a novel quick detachable cable connector and shield for a spark plug.

One embodiment oi the invention has been illustrated in the accompanying drawing, but it is to' be understood that said drawing is for purposes of illustration only and is not to be construed as a deiinition of the limits 'of the invention, reference being had to the appended claims for this purpose.

In Said drawing:

Fig. 1 is a sectional elevation oi. one embodil ment of the invention;

Fig. 2 is a section taken on the line 2-2 of Fig. 1; and

Fig. 3 is a perspective view showing in detail the various elements of the spark plug shown in Fig. 1 and their relation to oneanother.

Referring now to the drawing, wherein like reference numerals indicate like parts throughout the several views, Figs. 1 to 3 illustrate an ignition device for internal combustion engines which includes a novel spark plug embodying means for forming a gas-tight seal to prevent the escape of gases under compression from the engine cylinder. In the form shown, said plus.r comprises a body portion I which is exteriorly threaded for engagement with the cylinder wall ofy an internal combustion engine, a portion of which is indicated at 2, the outer portion of said body being oi' increased diameter to provide an inner shoulder 3. An electrode I, which is positioned centrally in the body I, is provided at its lower end with an enlarged head 5 in which is secured a terminal 6. The other end of the electrode is threaded at 1 for a purpose to be described hereinafter, and an insulator 8, preferably a mica sleeve, surrounds the electrode 4 between the head 5 and the threaded end l. A plurality of insulating washers 9, preferably'of mica, surround the lower portion of the electrode l and insulating sleeve 8 adjacent the head 5, said washers preferably being of increasing outer diameter away from said head. A substantially cup-shaped electrode III, the bottom of which is provided with a plurality of perforatons `II through one of which extends the terminal 6, has its rim bent radially outward at I2 to form a flange engaging the shoulder 3 formed in the body l.The electrode l0 is held in said bodyv by suitable means which in the form shown comprises a wedge I3 bearing against the top washer 9 and having an inclined surface I4 which is pressed against the ange I2 by means of a gland I5 threaded in the outer enlarged portion of the body I and adaptedto engage a shoulder IB formed on said wedge. As shown in the drawing, both the gland I5 and body I are provided with polygonal portions.

A plurality of insulating washers I1 surround the upper portion of the electrode 4 and insulating sleeve 8 and rest `ori the gland I5, said washers preferably decreasing in diameter toward the threaded end 1, and a terminal member I8 is screwed onto the threaded end 1 of the electrode. Suitable mearis is provided for attaching a cable or lead to said terminal member which in the form shown comprises a split spring tip or post I9. The head 5 and the threaded engagement between terminal member I8 and electrode 4 provide means for tightly ber 22 is assembled with the Wedge and gland.

I5 is engaged with the wedge and member 22,

As shown in Fig. 3, the upper portion of wedge I3 is provided with suitable serrations adapted to engage cooperating serrations provided on the inner surface of gland I5. The parts thus assembled are subjected to pressure in a suitable press, or, in certain instances, the pressure may be applied after insulation I1 has been assembled on the electrode. The pressure is ef fective through the inclined surfaces of the gland and wedge to force the relatively soft member 22 into intimate contact with the insulating sleeve 8 whereby the latter is wedged into engagement with the center electrode and a double gas vseal is formed around the electrode. The structure thus assembled is now threaded into body I to hold the same together with cup I8 in operative position. It will be seen that flange I2 of member III is held in close engagement with shoulder 3 by wedge I8 to form a gas tight joint at this point. If desired, flange I2 may be doubled upon itself so as to allord an extra thickness of metal at the point of engagement with shoulder 3 and wedge I3, thereby insuring the gas-tight integrity of the joint. This construction may render it unnecessary to employ the usual gasket at this position. The use of the serrations and the pressure applied to the parts are effective to prevent rotation of wedge I3 relative to insulation 8 whereby the seal at this point is preserved. The wedge and gland, after assembly, constitute in effect an integrally formed member and retain member 22 in operative position, as well as the remaining elements.

A lead or cable 25 is connected to the terminal post I9 in any suitable manner and, as shown, is provided with a terminal ring 26 which is adapted to slip over the split terminal I9, said cable being covered by suitable' insulation 21 carrying a metal shield which may be formed of woven wire, for example.

Preferably, the end of the cable 25 and. the terminal ring 26 are secured in an insulating and shielding housing which may be placed over the outer end of the spark plug to engage ring 28 with the terminal post I9, suitable means being provided whereby said shielding member is rotatably secured to the spark plug structure. In the form shown. the shielding member comprises a substantially L-shaped metallic casing or elbow 28, one of the arms thereof being adapted to fit over the outer end of the spark plug and the other arm housing the end of the cable 25. V.ein insulator 89, formed of porcelain or other suitable insulating material, is disposed in the elbow 28 and is provided vwith openings for the entrance of the cable and the upper end oi the spark plug.

Preferably, the elbow 28 is detachably secured to the spark plug structure by means which is rotatable around the spark plug to permit angular adjustment of the cable. In the form shown, the lower end of the elbow 28 is provided with one or more pins 80 which are adapted to engage bayonet slots 3i in a ring or sleeve-like member 32 that is rotatably mounted on the spark plug structure in any suitable manner. Preferably, th'e body I of the plug is provided with an outerilange or shoulder 33 and the 'ring 32 has a suitable inner ilange or shoulder 34 which engages under said shoulder 33. Suitable resilient means, such as a coil spring 35. are preferably interposed between the flange 3s and a suitable shoulder 38 on the casing 28, said spring being compressed bypushing downwardly on the casing 28 to engage the pins 30 in the bayonet slots 3i.

There is thus provided an improved spark plug construction which is both' mechanically and electrically strong, all of the parts being rigidly assembled in a compact structure securely mounted in the engine cylinder wall. Said construction embodies novel means for sealing the cylinder to prevent the escape of gases under compression therefrom which means is adapted by the adjustment of a single member to effect a double engagement with the electrode whereby said electrode is doubly held and sealed against the escape of gases. Moreover the projecting outer portion of the spark plug together with the supply cable and the terminal connection between the cable and the electrode are all completely insulated and shielded. The novel shielding means may be quickly and easily attached and locked to the spark plug body, or removed therefrom, by the simple operation of placing the shield over the plug and engaging the pins 30 in the slots 3i, and the shield may be adjusted to any desired angular position around the axis of the plug due to the rotation of th'e ring 32 on the plug. The housing or shield not only completely surrounds and shields the plug and its connection with the cable, but also, owing to the split terminal post and the terminal ring, the shield and cable may be attached or detached as a unit with great facility. It will be obvious that the invention is not limited to the form described and illustrated in the drawing, but is capable of a variety of embodiments. Similarly, changes may be made in the form, details of construction and arrangement of the parts without departing from the spirit of the invention, and it will be understood that the shielding means may be employed with spark plug structures other than that illustrated. Reference is therefore to be had to the appended llaims for a deilnition of the limits oi' the inven-` What is claimedis:

l. Apparatus of the character described comprising in combination 'a spark plug body, an electrode extending therefvnam, a cable connected to said electrode, means for housing and shielding said electrode and cable comprising an insulating elbow into one arm of which said cable extends, the other arm ntting closely about the plug body, a metallic covering on said elbow, a ring rotatably mounted on said body, and adjustable to any position angularly thereof prior to attachment of said body to the engine. and means :for holding said ring against angular Amovement thereafter.

2. Apparatus of the character described, comprising in combination a spark plug body and an electrode, said body having a iange, a ring having means rotatably engaging the under surlace of said flange to be clamped in position thereby, a metallic elbow having a portion surrounding said electrode and telescoping with said ring, means for connecting said elbow and ring, a cable extending into said elbow and connected to said electrode, and means including a second elbow for insulating said cable and electrode from said rst named elbow.

3. Apparatus of the character described comprislng, in combination, a spark plug body including a metallic flange, means including an electrode carried by said body, said electrode extending upwardly from the body, a metallic elbow, an insulator elbow integral with said metallic elbow and having one arm thereoi formed to fit closely about the plug body and the other arm provided with a bore to receive a cable, a shielded cable extending into said bore, a cable terminal carried by said cable and adapted to engage said electrode in the horizontal plane o! said bore when the elbows are placed thereover, and means including a metallic ring engaged with said ilange for detachably connecting said elbows to said body.

4. In apparatus of the class described, the combination with a spark plug body o! means including an upwardly extending electrode carried by the body, a metallicelbow, an insulator elbow within the metallic elbow, one arm of said insulator elbow surrounding the electrode and the other arm being provided with an opening to receive a cable, a cable extending through said opening, a cable terminal adapted to engage said electrode when the elbows are placed thereover, a member rotatably mounted on the body, and means for securing said elbows to said rotatable member in one predetermined angular position only.

5. In combination with a spark plug, having a body portion provided with a circular shoulder, a ring having engagement with said shoulder, a metallieelbow having telescopic engagement with said ring, bayonet-joint means for removabLv connecting said elbow and' ring, yielding means having engagement with the elbow and with said shoulder for maintaining the bayonetjoint means in operative engagement, an in- I sulator elbow in the metallic elbow and having one arm surrounding the upper portion oi the spark plug, the other arm oi the insulator elbow being provided with a bore, a shielded cable extending into said bore, and means for operatively connecting said cable and plug.

`6. In combination with a spark plug having a body portion provided with a circular shoulder, a ring surrounding said body portion and having engagement with the lower surface oi said shoulder, an elbow having telescopic engagement with 4said ring and surrounding the upper portion of the spark plug, means tor detachably connecting said elbow and ring, yielding means between said elbow and ring for maintaining said connecting means in operative position, insulating means within said elbow having an opening therethrough, the upper part of the spark plug ex` tending through a portion oi said opening, and a lead-in wire extending through another portion oi said opening, and means for operatively connecting the lead-in wire with the spark plug.

'1. Means for housing and shielding a spark plug and associated cable comprising a metallic elbow into one arm of which said cable extends, the other arm surrounding said plug, means permanently integrated with said metallic elbow for insulating said elbow from said plug and cable, a ring rotatablymounted on and clamped in position by said plug. and means for connecting said ring and elbow.

8. A spark plug shield comprising a metallic elbow, an insulator elbow integral with said metallic elbow and having one arm thereof formed to ilt closely about the spark plug and the other arm provided with a bore to receive a cable, and means clamped in position by said spark plug for detachably connecting said elbows lto said spark plug.

9. Means for shielding and housing a spark plug comprising a ring member coaxial with said spark plug, a metallic elbow having telescopic engagement with 'said ring, means for removably connecting said elbow and ring, yielding means having engagement with said elbow for maintaining said last named means in operative engagement, an insulator elbow integral with the metallic elbow and having one arm surrounding the upper portion of said plug, the other arm of the insulatorelbow being provided with a bore, a shielded cable extending into said bore, and means for operatively connecting said cable and plug.

l0. A shield lor a spark plug comprising, in combination with an insulating elbow surrounding the upper part of the plug, a sleeve having a slotted portion at the upper end thereof, said sleeve surrounding a portion of said plug and elbow, and a metallic elbow having a cooperating projecting pin for engagement with said sleeve and retained in operative position by said pin, said sleeve being angularly adjustable about the longitudinal axis oi the plug prior to attachment of the plug to the engine cylinder but angularly fixed thereafter.

11. A spark plug comprising in combination with a metallic shell and a shielded cable disposed at right angles to the longitudinal axis of said shell, a metallic sleeve secured to the shell, and a metallic elbow engageable at one end with said conductor and at the other end with said sleeve, said elbow having a pin and bayonet slot engagement with said sleeve to electrically connect the shield on said conductor with said sleeve and shell.

i2. In combination with a spark plug having a body portion provided with a shoulder, a metallic member having a portion extending under said shoulder, a second metallic member having telescopic engagement with said `ilrst named member, bayonet joint means for holding said two metallic parts against relative movement, an insulator elbow within said second metallic member and having one arm surrounding the upper portion of the spark plug, the other arm of the insulator elbow being provided with a bore, a shielded cable extending into said bore, and means for operatively connecting said cable and plug.

13. In 4combination with a' spark plug having a body portion provided with a shoulder, a metallic member having a portion extending under and clamped in position by said `shoulder, a second metallic member having telescopic engagement with said i'lrst namedmember'. means for holding said two metallic parts against relative movement, an insulator elbow within said second metallic member and having one arm surrounding the upper portion of the spark plug, the other arm of the insulator elbow being provided with a bore, a shielded cable extending into said bore, and'means ior operatively connecting said cable and plug.

14. In combination with a 'spark plug having a body portion provided with a shoulder, a metallic sleeve having a portion extending under said shoulder, a second metallic member having engagement with said sleeve, a retaining part projecting from said second member into engagement with said sleeve, and resilient means engageable with said second metallic mem-ber to supplement the retaining action of said last named part.

15. In combination with a spark plug having a body portion provided with a metal shoulder, a metallic member having a portion extending under said shoulder, a second metallic member having engagement with the first, a retaining part projecting from one of said members into engagement with the other, and additional retaining means engageable with said second metallic member.

16. A spark plug covering comprising an L- shaped metallic sleeve clamped in position by the lower part of the plug, and an insulating elbow whose surface conforms to the inner conremovably connecting said elbow to said annular member, yielding means having engagement with said elbow for maintaining said .last named means in operative engagement, an insulator integrated with said metallic elbow, a shielded cable extending into said.insulator, and means for operatively connectingsaid cable and plug.

18. In combination with spark plug having a body portion provided with a shoulder, an annular metallic member having-a portion extending undersuch shoulder, ametallic elbow having telescopic engagement with saidannular member, means for removably connecting said elbow in proper angular relation to said member, yielding means having engagement with said elbow for maintaining said last named means in operative engagement, an insulator integrated with said metallic elbow, a shielded cable extending into said insulator, and means for operatively connecting said cable and plug.

19. In combination with a shielded conductor and a spark plug including a metal shell having a wrench receiving portion and a shoulder below said wrench receiving portion, a device for 'preventing radiation of electrical energy therefrom comprising a casing fo-rmed of complementary sections, one of which has an apertured portion for engagement with said shoulder and a portion of Wider bore surrounding but spaced from said wrench receiving portion, and means adapted to hold said sections in contact with each other.

20. In combination with a spark plug having a metal body portion provided with a shoulder, a metallic member having a portion extending under said shoulder, a seco-nd metallic member having engagement with the iirst, and additional retaining means engageable with one of said metallic members.

21. In combination with an engine cylinder, a spark plug and a radio shielded cable therefor, a spark plug shield comprising a metallic cup rigidly secured to the cylinder by the spark plug, a dielectric cap disposed over the cup and a metallic sheath on said dielectric cap.

22. In combination with an engine cylinder a spark plug and a radio shielded cable therefor, a spark plug shield. comprisingv a metallic cup rigidly secured to the cylinder by the spark plug, a dielectric cap disposed over the cup and a metallic sheath on said dielectric cap, said cap forming a moisture proof closure for said cup.

23. In .a shielding system for the ignition elements of a radio receiver-equipped vehicle, a shielding device comprising a plurality of telescopic members adapted for adjustable positioning upon an ignition element, and means urging said members into extended position.

'24. In a shielding system for the ignition elements of a radio receiver-equipped vehicle, a

shielding device comprising a plurality of telescopic members adapted for adjustable positionplug, one of said members being adapted to electrically engage a grounded conductive portion of the plug, and means for urging said member into good electrical contact with said grounded portion of the plug. y y

26. In a spark plug of the type having a central electrode and an angularly directed shielded conductor electrically connected thereto, the com bination withV said conductor and electrode of shielding means including a cylinder engaging shell, a second cylindrical'shelding member connecting electrically with said shell, a third shielding member embracing the end of the angularly directed conductor and electrically connected with the conductor shielding and second shielding member, whereby. lan electrical shielding circuit is maintained between the shielding of the conductor and the cylinder engaging shell, by way of said second and third shielding members, and insulating means including a dielectric body having intersecting passages, one to receive the body of the plug and the "other to receive the end portion of said angularly directed conductor for ready attachment to the end of said electrode within said dielectric body in mounting said dielectric body with its shielding on said plug.

27. In a spark-'plug of the type having a central electrode and an angularly directed shielded conductor electrically connected thereto, the combination with said conductor and electrode of shielding meansincluding a cylinder engaging shell, and complementary means embracing the end of said angularly directed conductor and electrically connected with the conductor shielding and shell, whereby an electrical shielding circuit is maintained between the shielding of thev conductor and said cylinder engaging shell, and

insulating means including a dielectric body embracing the body of the plug and into which'dlelectric body said' conductor is lnsertible from one end of said body to a depth suiiicient to cause the end portion of said conductor to be disposed in a position of adjacency and ready attachability to the outer end of said central electrode disposed within said dielectric body.

28. In a spark plug radio shield, a shielding cap adapted to .5e placed over a spark plug comprising a dielectric body formed with a bore to receive an ignition conductor, a contact means carried by the cap in contact with a spark plug and also in contact with the ignition conductor, said cap being formed with a dielectric skirt surrounding the upper portion of a spark plug, and a metallic covering on the outside of said dielectric body.

29. in a spark plug radio shield, a shielding cap adapted to be placed over a spark plug comprising a dielectric body formed with a bore to receive an ignition conductor, a contact means carried by the cap in' contact with a spark plug and also in contact with the ignition conductor, said cap being formed with a dielectric skirt surrounding the upper portion of a spark plug, and shielding means enclosing said dielectric body.

EDWARD B. ,NOWOSIELSKL 

